Earnings Per Common Share (Summary Of Computation Of Basic And Diluted Earnings Per Common Share) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Earnings Per Common Share [Abstract]
Income available to common shareholders	$ 18,917	$ 18,125	$ 67,138	$ 57,167
Denominator for basic earnings per share (weighted average common shares outstanding)	15,398,909	15,272,720	15,398,919	15,090,113
Effect of dilutive options and warrants			1,722
Denominator for diluted earnings per share (weighted average common shares outstanding adjusted for the effect of dilutive options and warrants)	15,398,909	15,272,720	15,400,641	15,090,113
Basic earnings per common share	$ 1.23	$ 1.19	$ 4.36	$ 3.79
Diluted earnings per common share	$ 1.23	$ 1.19	$ 4.36	$ 3.79

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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- Definition

The sum of dilutive potential common shares or units used in the calculation of the diluted per-share or per-unit computation.

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- Definition

The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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- Definition

Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

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-Glossary Weighted-Average Number of Common Shares Outstanding

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